The invention relates to a mechanical speed governor, wherein a stepper or servo motor is provided for correcting the quantity of fuel delivered by a fuel pump in the range of full-load and starting speeds of an internal combustion engine. As control unit is provided to process internal combustion-engine and ambient parameters for controlling the stepper-servo motor, which influences the regulating displacement of a quantity-control member of the injection pump in such a way as to correct the quantity of fuel delivered by an injection pump of compression ignition internal combustion engines provided with an electronically controlled adopting device.
DE 3,430,797 Al discloses a speed governor having an electronically controlled adapting device with which the fuel quantity can be corrected. The delivery quantity of the injection pump can be automatically adapted to the fuel requirement of the internal combustion engine in full-load and starting range in order to reduce (as far as possible) damage to the environment and in particular the emission of hydrocarbons.
An object of the instant invention is to create a speed control on a mechanical speed governor having electronically controlled adaption whose quantity-correction range covers the full-load range of the engine and is also used for control during the starting range. In the event of the electronic system failing in the starting position, the speed control will cover a controllable speed range which does not extend beyond the full-load range
The object is achieved according to the invention by having the electronically controlled adapting device comprises a two-step stop which is in operative connection with the fuel quantity-control member to limit the starting and full-load quantity and wherein the stop can be transferred as a function of speed from a position corresponding to the starting speed into a position corresponding to the full-load speed.
The invention ensures that in the event of a fault in the adapting device in the starting position, the internal combustion engine is not constantly operated with starting quantity at full load and thus at worst destroyed by overheating. Furthermore, despite the emergency-travelling facility, an electronically controlled adaption with small adapting displacements is possible during regular operation of the internal combustion engine. That is no adaption covering the entire range from full load up to starting quantity is necessary, but merely an adaption which covers the full-load range, since when the two-step stop is shifted the adaption also becomes effective for the starting range.
It is further advantageous if the two-step stop is arranged on a transmission lever connected to the stepper-servo motor to interact with a counterstop on the quantity adjusting member. The quantity-adjusting member consists of a control rod and an fork which contains the counterstop and is connected in an articulated manner to the control rod. The counterstop is formed by an adjustable pin. The transmission lever is designed as a pivot mounted strap, which at its free end has two steps arranged to lie one behind the other in the operative direction of the stepper-servo motor. The first stop (limiting the full-load quantity) is effective when the strap is pivoted to the top, and the second stop (limiting the starting quantity) is effective when the strap is pivoted to the bottom.
The strap has a slotted link on which the adjusting member producing the pivoting movement of the strap is guided as a link slide.
The adjusting member is designed as a double-arm lever and is in operative connection with a centrifugal-weight device of the speed governor.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.